Metal reinforcement for abrasive teeth



c- 1937- G. w. 'CHORMANN ET AL 2,102,306

METAL REI NFORCEMENT FOR ABRASIVE TEETH I I Filed April 24, 1956 3 Sheets-Sheet l INVENTOR. GEORGE W. GHORMANN BY v HARRY J. GOMHE W ATTORNEY.

Dec. 14, 1937. G. w. CHORMANN ET AL 1937. G. w. CHORMANN ET AL METAL REI FORCED/1M5? FOR ABRASIVE TEETH Filed April 24, 1936 3 Sheets-Sheet 5 INVENTOR. GEGRGE W. CHORMANN HARRY J. COWIE Wyn/MIA ATTORNEY.

Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE METAL REINFORCEMENT FOR ABRASIVE TEETH George W. Ohormann,

Niagara. Falls, N. Y., and

Application April 24,

Claims.

This application relates to the mounting of abrasive teeth for stone saws and relates particularly to metal reinforcements for portions of such abrasive teeth where they become engaged 5 with clamping surfaces of the support. The present application is a continuation in part of our copending application, Serial No. 688,640, filed September 8, 1933.

In making deep cuts in marble, limestone, and the like, it is often possible to speed up the cutting action by using a saw blade in which there are inserted teeth formed by molding (under suitable temperature and pressure conditions) a mixture of bonding material and abrasive grain. This saw blade may be mounted for rotation or for reciprocation. In either case, the insert teeth are mounted in the saw blade by clamping the root portions of the teeth in sockets formed in the blade, the clamping being completed by the 20 insertion of wedges. In the United States Patent No. 1,198,871 there is disclosed a saw tooth composed of bonded abrasive which is adapted to be mounted in a saw blade provided with suitable sockets.

While such stone saws have, for the most part, operated satisfactorily, it has been necessary in the production of the saw teeth to guard carefully against inaccuracies in the molding of the socket-engaging edges of the roots of the teeth. It is, for example, quite necessary that the bevelled edges be accurate and smooth in order that the teeth may fit properly in the sockets in the saw blades. During the molding of the saw teeth, there is a tendency for the excess abrasive material to squeeze out between the meeting or complementary edges of the dies or mold halves. As the material being molded is highly abradant, the molds or dies become worn at the edges after a relatively short time. When this happens, the 40 socket-engaging edges of the root of the tooth are no longer accurate. Some of the disadvantages arising from inaccuracies in the shape and fit of the teeth in the saw can be readily understood. If one abrasive tooth, for example, should be mounted so as to be displaced slightly toward one side or the other, this one tooth will bear the strain of grinding or cutting in a slightly offset channel. Breaking of the tooth is almost sure to ensue. The improvements which we have made in abrasive teeth for stone saws and in the method of making them are concerned with the provision of metallic reinforcements for the socketengaging edges of the teeth and with the methods of making such metallic reinforcements and of incorporating them in the abrasive teeth.

1936, Serial No. 76,278

The invention is illustrated by means of the accompanying drawings in which:

Fig. l is a side elevation of an abrasive tooth reinforced along the socket-engaging edges in accordance with the present invention;

Fi 2 is an elevation of the side of the tooth opposite to that shown in Fig. 1;

Fig. 3 shows a blank of sheet metal, dots and dashes being used to indicate the lines along which the metal blank is subsequently deformed in making the metal reinforcement;

Fig. 4 is a plan View of the metal blank after it has been deformed by means of a suitable die so that the edge portions (outside the lines indicated by clashes in Fig. 3) are inclined to the flat base that lies within said lines;

Fig. 5 is a section on the line V--V of Fig. 4;

Fig. 6 is a perspective view of the metal rein-. forcement after the edge portions have been bent (along the lines indicated by the dots shown in Fig. 5 and in Fig. 4), and after a portion of the base has been cut away subsequently to the forming of the bent edges;

Fig. 7 is a plan view of the lower die of a mold used for forming an abrasive tooth for a stone saw;

Fig. 8 is a section on the line VIIIVIII of Fig. 7;

Fig. 9 is a sectional elevation through a complete mold showing the metal reinforcement in position, the section of the lower die being taken on the line IX1X of Fig. 7;

Fig. 10 is a sectional elevation of the mold (in the same plane as Fig. 9), from which the principal upper die has been removed and into which means for introducing the abrasive mix into the mold has been inserted;

Fig. 11 is a section of the finished abrasive tooth taken on the line XIXI of Fig. 1;

Fig. 12 is a section of the finished abrasive tooth taken on the line XII-XII of Fig. 1;

Fig. 13 is a side elevation of a modification of the abrasive tooth shown in Fig. 1;

Fig. 14'is a section on the line XIVXIV of Fig. 13;

Fig. 15 is a section on the line XVXV of Fig. 13; and

Fig. 16 is a fragmentary side elevation of a portion of a metal saw blade with an abrasive tooth mounted therein.

Referring to the drawing in detail, a blank 2 of thin sheet metal is indicated in Fig. 3, the blank being of a shape which can be stamped and bent into a metal reinforcement for the socket-engaging edges of an abrasive tooth of the type shown Fig. i. and Fig. 2. The blank 2 is placed on a suitable die and is stamped to form inclined edge portions 3 that project at similar angles to the base 4 as indicated in Fig. 5. The inclinations of the edge portions'3 to the base 4 are approximately the same as the corresponding inclination of the bevelled surfaces of the root of the finished tooth to an adjacent flat 7 side. The extended edges 3 of the stamped metal blank are then bent back (along the lines indicated by dots in Fig. 4) to form the edge portions 5. which are indicated in Fig. 6, leaving three bevel edges having respective faces indicated by' the reference numbers 5 and 6. V

A portion of the base is subsequently cut away. to form the metal reinforcement in the approximately final formshown in perspective in Fig. 6. The shape of the original metal blank is such that notches or slits I are left between the long flap 5 and the shorter lateral flaps 5. The bevel angles between the flaps 5 and the adjacent edge portions 6 are made a little greater than the corresponding bevel angles on the root of the finby means ,of amold box I4 During the early part of our efiortsto produce. anfimproved tooth, we usedan upper die com- 'plemental to the lower die I3, and compacted 7 an abrasive member between the two dies, mold- "ing the abrasive mixlinto'intimate contact with the metal reinforcement during the pressing operation. High pressures, for example 2000 pounds per square inch, were used in pressing,

. and we found that during molding there was a tendency for the metal reinforcement to .be squeezed outwardlybetween the edges of the two dies as they approached each other. The result was that a metal fin was formed on the edge of the root ojf the tooth. This fin'interfered with the accuracy of the fit of the abrasive tooth in the socket of the saw blade. In the present construction; as illustrated in the drawings, we have provided an overfiowchamber' I5 (for excess abrasivemix) which is formedin the dies just outside the main chamber in which the abrasive tooth is formed, as indicated particularly in Fig. 9'and in Fig. 10. Moreover, theupper die which jwe originally used has been replaced by two dies I6 and, H. The member 16 is themain' upper 7 die The member Il may be called a supplemen- I tal die. This supplemental die overlies and confines the overflow chamber- [5. 7 When pressure is applied'to the mixin the main chamberthrough the upper die Hi, the metal edge is'held in position by the weight of the supplemental'die "and its friction against the adjacent members. Overflow of abrasive material occurs especially beyond the limits of the metal edge in the chamber ;I.5. The overflow mix is thus kept substantially separated from the main body of the mix (that f is usedto form the abrasive tooth). by means of the metal reinforcement l and theconfining action of thesupplemental 'die 11.

In preparing for the molding operation, the

lower die I3' is placed in the box l l'along with 7 the metal reinforcement I and the supplemental die [1. Thebevelled edges of the metal reinforcement are inserted between corresponding in- 7 clined surfaces on the lower die and on the supplemental die respectively. In order to introduce the abrasive mix onto the lower die I3, a

cylindrical container l8 which is open at the ends, is placed over the lower die, and filled with a weighed amount of the abrasive mix which is to constitute the body and root of the tooth. To ensure complete filling of the mold cavity. under pressure a slight excess of mix over the calculated amount may be placed'in'the container, the

overflow chamber 15 being used in the subsequent procedure to take care of such excess material as may be introduced into the container [8. The

mold and its contents (as indicated in Fig. 1o

are then placed in an oven and raised in temperature to make the bond (for example, shellac) suificiently plastic so'that the mix may flowunder pressure in the subsequent forming operation.

After this temperature has been reached thei assemblage is removed from the oven, the container I8 is removed, and the upper die It is placed on the mix and pressed down into the po'-- sition indicatd in Fig. 9. The abrasive mix is, however, not shown in Fig. 9. The pressing operation causes. the plastic mixture of abrasive grain and bond to flow'into all parts of the mold cavity and brings it into close contact with the metal reinforcement. is simultaneously reshaped to make it accurately fit against the complementary inclined surfaces of the dies. To enable this fitting operation to be carried out more effectively, the metal reinforcement is preferably formed as mentioned above with its projecting edges slightly spread;

When the high pressure used for compacting the abrasive mix is applied to the dies, the projecting edges of the'metal reinforcement are forced The metal reinforcement inwardly so that the socket-engaging edges of the root of the tooth may be accurately aligned.

The shaped tooth may then be cured in any suitable manner. The bond may be a heat-hardenable resin or a thermoplastic resin. In' the latter case the bond is plastic during the press ring operation whichfma'y be performed, for example, by placing-the mold between heated platens. The bond then hardens subsequently during the cooling of the molded article.

' In Figures 1, 2, 11, and 12 we have shown in detailan abrasive saw tooth produced in accordance with our invention. In the form of abrasive tooth illustrated in these views, the metal reins forcement is largely confined to the edge portions of the root of the tooth, the base 4 of the stamped blank having been largely cut away before the metal reinforcement was placed in the mold. Iti

is desirable to retain portions of the base of the stamped blank from considerations of mechanical strength, asfor example the portions l9 and 20' .60

adjacent the slit corners of the metal reinforce ment; A narrow strip of the base of the stamped blank may also be retained at'2l to strengthen the formed, metal reinforcement against deformation in planes parallel to the lines on which the three extending edge portions of the stamped blank are folded.

The V'shapes'of the edges of the toothroot are evident from Figures 6, 11, and 12. The root of l the tooth has three bevelled edges and is adapted to be clamped in the sockets}! of the. saw blade 23," a fragment of. which is shown in Fig.' 16.' Grooves 24 aiongthe'two side s of the socket 22 engage respectively two bevelled edge portions of the root 25 that converge outwardly. from the.

base of the'socketJ The metal'surfaces on these lateral edges of the root of the tooth fit closely against the corresponding surfaces of the lateral V-shaped grooves of the socket.

The lower V-shaped edge 26 of the tooth cooperates with a wedge 21. This wedge may be inserted between the edge 26 of the root and a rib 28 on the saw blade 23. When the wedge is driven into close engagement as indicated in Fig. 16, it holds the root of the tooth in position in the socket 22. To assist in retaining the wedge in position, the grooves of the wedge and the corresponding surfaces 26 of the edge of the tooth and the rib 28 can be knurled in such a direction that it is easier for the Wedge to move into close relation to tooth and blade than it is to move in the opposite direction.

In Figures 13, 14, and 15 we have shown a modified form of our abrasive tooth in which one side of the root of the tooth is covered with a metal reinforcement which is integral with the metal surfaces that cover the socket-engaging edges of the root of the tooth. This metal reinforcement is made from a blank 2 like that shown in Fig. 3, in the same way as described above except that the base of the stamped and folded blank is not cut away. The form of metal reinforcement just described is molded along with the abrasive mix in the manner described above in connection with Figures 9 and 10.

As the abrasive tooth becomes more and more worn, the leading portion of the side face of the metal reinforcement illustrated in Figs. 13, 14, and 15 becomes worn off. This may result in loosening a portion of the metal side face from the root of the abrasive tooth. As a further improvement in such an abrasive saw tooth we propose to anchor or embed a portion of the sheet metal reinforcement in the interior of the tooth. The metal side may be slit to a small extent on the upper edge, the points turned inward, and the metal molded in position along the abrasive mix as described above. This leaves a metal reinforcement having inward projections that are embedded in the interior of the tooth. We prefer, however, to break and turn inwardly portions of the metal blank as indicated at 29 in Fig. 13, a convenient tool for this purpose being a center punch. The inwardly bent portions become embedded or anchored in the abrasive material during the molding process.

Since water is used in the stone-cutting process, it is desirable that the metal reinforcement should be resistant to the action of water, and may be fashioned, for instance, of stainless steel.

The product we obtain has the very considerable advantage that the socket-engaging edges are smooth and carefully molded to shape. The angle of bevel, which is an important feature of the root of the tooth, is made under conditions which ensure correct positioning of an abrasive tooth in its socket in the saw blade. The cost of the product, due to the elimination of the truing up step after molding, is low.

The teeth are less destructive of the sockets and wedges while being inserted and removed from their positions in the blade than a tooth which has abrasive edges. At times the teeth engage the socket surfaces and the wedges with considerable pressure. With uncovered abrasive material applied against the socket surfaces and the wedges, any relative movement will cause wear of these surfaces. The metal edges of our improved abrasive tooth slide on the grooved surfaces of the saw blade socket with relatively light friction. The socket grooves have therefore a correspondingly long life.

We claim:

1. An insert tooth for a stone-cutting saw comprisingan abrasive member having a body and a root both flattened to enter a relatively narrow kerf, and a sheet metal sheath enclosing edges of said root and extending across at least one lateral face of said root, said edges being bevelled to conform to a V-shaped socket and the sheath being correspondingly shaped.

2. A metal sheath for an abrasive saw tooth consisting of a sheet of metal having a fiat base, the edges on three sides extending slantingly upward and then extending upward on a reversed slant to form V-shaped channels, the corners between three sides having slits extending from the edges of the sheet.

3. An insert tooth for a stone-cutting saw comprising an abrasive member having a body and a root molded integral from a mixture of bonding material and abrasive grains, and a sheet metal sheath enclosing the edges of said root and extending across at least one lateral face thereof,

the latter portion of the sheath being anchored to the root by an inward extension embedded in the material of the root.

4. An insert tooth for a stone cutting saw comprising an abrasive member having a body and root both flattened to enter a relatively narrow kerf, the edges of said root being bevelled to conform to a V-shaped socket and a sheet metal sheath enclosing the edges of said root and extending upwardly at the bottom and inwardly at the sides of at least one lateral face of said root.

5. A metal sheath for an abrasive saw tooth consisting of a piece of metal having a fiat base of substantially U-shape, the edges on three sides extending slantingly upward and then extending upward on a reversed slant to form V- shaped channels, the corners between three sides having slits extending from the edges of the U-shaped base.

GEORGE W. CHORMANN. HARRY J. COWIE. 

